A laser (e.g., semiconductor laser diode (LD)), a light-emitting device (e.g., light-emitting diode (LED)), a light-receiving device, a hybrid optical device, an optical integrated circuit, and the like have been known as optical devices. In recent years, an optical device which is blue or white light having a short emission peak wavelength has been developed, and widely used. Since the brightness of light-emitting devices with a short emission peak wavelength has remarkably increased, the amount of heat generated by the optical devices tends to increase.
An optical device is normally used as a sealed optical device in which the optical device is sealed with a cured product of a sealing material.
A sealing material which mainly contains a transparent epoxy resin that produces a cured product exhibiting excellent heat resistance, etc. has been known as an optical device sealing material.
Along with an increase in brightness of optical devices, however, the cured product of the optical device sealing material is exposed to high-energy light or a high temperature generated by the optical device for a long time. This may cause a deterioration in the cured product, so that cracks or yellowing (coloration) may occur. The optical device may not be continuously used when cracks have occurred in the cured product of the optical device sealing material. A decrease in transparency may occur when coloration has occurred, so that the brightness of the optical device may decrease.
In view of the above problems, Patent Documents 1 to 3 disclose an optical device sealing material which contains a polyorganosiloxane compound as the main component. Patent Documents 1 to 3 disclose that the polyorganosiloxane compound enables production of a sealed optical device which exhibits excellent crack resistance and heat resistance.
However, when using a cured product of the optical device sealing material disclosed in Patent Documents 1 to 3 which contains the polyorganosiloxane compound as the main component, it may be difficult to sufficiently prevent yellowing which may occur when the cured product is subjected to high-energy light or heat generated by the optical device for a long time. Therefore, development of an optical device sealing material which can produce a cured product which exhibits more excellent heat resistance has been desired.    Patent Document 1: JP-A-2004-359933    Patent Document 2: JP-A-2005-263869    Patent Document 3: JP-A-2006-328231